Bring insight to your recovery through isokinetic testing

Frequently Asked Questions

What is a CYBEX (isokinetic) Test?

A CYBEX Isokinetic Test is used to measure the maximum strength of a joint throughout its available range-of-motion (ROM). The test compares the involved side to the uninvolved side. Results are used to design rehabilitation protocols and help make return to sport and return to work decisions.

What is the difference between an Isometric, Isotonic, and Isokinetic Test?

Isometric resistance the speed is zero and maximum effort is measured at one point in the ROM. In other words, the joint doesn’t move and the muscle exerts force without changing its length.

Isotonic resistance the speed is variable, the load is fixed (example 25 lbs.) and maximum effort is measured at only the weakest point in the ROM. Here, the muscle changes its length as it exerts force.

Isokinetic resistance the speed is fixed, the load is variable (adjusting to keep the speed fixed), and maximum effort is measured at every point in the ROM. The unique ability to measure maximum effort throughout the entire ROM makes Isokinetic resistance the preferred objective measurement resistance.

Isokinetic machines are used to test the shoulder, elbow, wrist, hip, knee, ankle, and back. The typical test involves 3 to 5 repetitions for each side and takes about 15 minutes. Out and back is one repetition. For example, to test the knee extensors and flexors the patient is in a seated position. The test begins with the leg in full flexion. The patient kicks out to full extension and then returns their leg to the initial start position and continues until the test repetitions are completed. Results from each side are compared to identify any existing deficits.

Results are presented using a line graph and numeric parameters. Graphs provide a visual representation of the torque (force or effort) generated as the limb moves through the ROM. Injured and uninjured side curves are overlaid to make it easy to spot a dip in a curve, which may be an indication of pain or weakness. If a dip appears the point in the ROM is noted so treatment can be designed to reduce it.

Numeric parameters quantify the torque curves. Ideally, the results from the injured side and uninjured side are within 15% of each other. If not, additional physical therapy is typically recommended.

Why take a CYBEX Test?

Injures occur when exerting maximin effort. The CYBEX Test is a safe way to measure maximum effort throughout the ROM in the clinic before returning to sport or work.

Who uses CYBEX Isokinetic Testing?

Will my insurance cover an Isokinetic test?

Talk to your physical therapy office about how they bill for isokinetic testing. Every practice and insurance plan is different, and they will be able to provide you with accurate answers.

Why is it called CYBEX Test?

In 1970 CYBEX, a division of Division of Lumex Inc., released the first isokinetic testing dynamometer. The name was CYBEX I. Since then the name “CYBEX Test” has become synonymous with “Isokinetic Test.”

CYBEXtest.org is a public service sponsored by Computer Sports Medicine, Inc.